The aflatoxins are a family of mycotoxins of polyketide origin. The biosynthesis of this family of toxins is to be investigated using 13C- and/or 2H-labelled specimens of averufin, a probable intermediate precursor of sterigmatocystin and aflatoxin. Work to date has been devoted towards a total synthesis of his C20 anthraquinone ammenable to the introduction of labelled centers.